While this is good news for the immediate future, its stuff like this that makes my skin boil. Bitcoins are kind of like Elves. They rarely come into being, there's a finite number of them and each loss is a tragedy! 
But you can divide a bitcoin as much as you want, while you can't divide an elf 
Pfft.. any dwarven axe knows better!
I think that bitcoin losses in the short term are no big deal for the system as a whole.
It would be 'nice' to have an idea of how many coins are in circulation, but if it gets to the point where there appear to be few left and it's a concern that large stashes thought lost, could suddenly reappear and devalue the currency; then perhaps that would be the time to migrate to a new chain.
I'm guessing that would be centuries away, unless there is some IT apocalypse which destroys a large percentage of wallets.